The present invention relates to building structures, and more particularly to moldable thermal barriers for xe2x80x9chead-of-wallxe2x80x9d joint assemblies between top of walls and ceilings, xe2x80x9cperimeterxe2x80x9d joints between floors and vertical walls, and other joints, gaps, or holes in building structures.
Firestops are thermal barrier materials or combinations of materials used for filling gaps and openings such as in the joints between fire-rated walls and/or floors of buildings. For example, firestops can be used in walls or floors to prevent fire and smoke from passing through the gaps or openings required for cables, pipes, ducts, or other conduits. Firestops are also used to fill joint gaps that occur between walls, between a ceiling and the top of a wall (xe2x80x9chead-of-wallxe2x80x9d joints), and between a floor and vertical wall (xe2x80x9cperimeterxe2x80x9d joints).
So-called xe2x80x9chead-of-wallxe2x80x9d joints pose a number of challenges for the fireproofing industry. Walls are increasingly being made of gypsum wallboard affixed to a framework of metal studs capped by a horizontally extending track. Ceilings are increasingly being made by pouring concrete onto fluted steel. Although the distance between the horizontally extending track at the top of the wall is often fixed in relationship to the ceiling, the gypsum wallboards are subject to expansion and contraction due to motion of other building components, ground settling, or other causes.
For such head-of-wall joints, it is known to use mineral wool batt as a thermal resistant firestop material due to its ability to provide for cyclic movements in the wallboard material. The mineral wool is cut into separate sheets that are appropriately sized depending on the specific geometry of the fluted steel ceiling. The sheets need to be stacked and compressed (e.g., a minimum 50%) when packed into the joint gap. In some situations, a fireproofing material is spray-applied into the spaces of the fluted ceiling to supplement the mineral wool in the joint. In either case, the mineral wool approach requires labor and time.
After packing of the mineral wool batt into place above the wall, the construction worker must then spray an elastomeric coating, using a minimum one-eighth inch thickness, against the exposed side surfaces of the compressed mineral wool layers. The coating must overlap a minimum of one half inch onto the ceiling and wall surfaces. Thus, the use of mineral wool batt and elastomeric spray coating provides for the ability of the resultant firestop to accommodate some cyclic movement (compression and extension) in various components such as the gypsum wallboards on either side of the head-of-wall joint.
So-called xe2x80x9cperimeter barrierxe2x80x9d systems also typically employ mineral wool and elastomeric coating as firestopping material in the joint gaps between floors and the surface of a wall, which could be an interior partition or an external wall. In this case, the mineral wool batt must be packed tightly in the gap, to improve its fire resistance, and so that upon expansion of the gap due to shrinkage of the floor or movement of the wall, the mineral wool does not fall out of the gap and into the floor level below. An elastomeric spray coating is then applied onto the top face of the packed mineral wool batt, but in most cases the bottom of the mineral wool batt is not coated. This is often due to the fact that the wool batt must be accessed from below, requiring that ladders and spray equipment be moved downstairs and set up.
One objective of the present invention is to provide a more convenient and cost-effective method for installing a thermal barrier in intricately shaped openings and joint gaps such as are found in xe2x80x9chead-of-wallxe2x80x9d joints, xe2x80x9cperimeterxe2x80x9d joints, and other variously sized and/or intricately shaped gaps or openings such as penetrations through walls. For example, openings having plastic pipes or plastic-coated wires often require an intumescent firestopping material for sealing the space left by the plastic material after it has melted in the fire. Sometimes an intumescent caulk material is inserted into such penetration openings. In the case of larger diameter pipes, a metal collar is used to retain the caulk in place. In other cases, wrapped or bagged mineral wool with an intumscent material is inserted into the hole. In any case, installation of such firestopping is time-consuming and expensive.
Another objective of the invention is to provide novel thermal barriers that may be used conveniently and safely in hard-to-reach building or ship vessel joint gaps or holes. For example, the location of a head-of-wall joint next to an elevator shaft or crawl space would render difficult the installation of mineral wool/coating systems, because the task of coating both sides would be complicated by the lack of convenient access.
A still further objective of the invention is to enhance safety of installation. An applicator must climb up and down ladders on a frequent basis when working on head-of-wall joint assemblies. In the first instance, there is the fitting and hand-packing of mineral wool material into the joint gap. In the second instance, there is the coating of elastomeric material to create a continuous surface between the ceiling, firestop, and wall. In both cases, the ladder may require frequent repositioning, and this is especially the case where joint gaps extend lengthy distances of ten to twenty feet or more. Frequent climbing up and down ladders would also be required in xe2x80x9cperimeter barrierxe2x80x9d systems if it were desired to apply an elastomeric coating onto the bottom face of a mineral wool firestop that has been packed between a floor and a wall, because the installer would need to go to the floor below the firestop to coat the bottom face of the mineral wool material.
In view of the prior art disadvantages, novel thermal barriers and methods are believed to be needed.
In surmounting the disadvantages of the prior art, the present invention provides a method and system for installing a thermal barrier in openings and gaps in or between building structures such as walls, ceilings, and floors. In so doing, the present invention provides increased convenience, effectiveness, and safety in comparison to the prior art mineral wool/coating methods. The thermal barriers of the present invention have the ability to conform intimately with the shape of openings and gap spaces of various sizes and shapes. The thermal barriers also have the ability to permit movement of the various building structures around the openings or gaps. In particular, protection on both sides of xe2x80x9chead-of-wallxe2x80x9d joint assemblies (arising between a wall and ceiling) as well as upper and downward faces of xe2x80x9cperimeter barrierxe2x80x9d assemblies (arising between a floor and wall) may be conveniently accomplished by the thermal barriers and methods of the present invention.
An exemplary method of the present invention comprises providing a first structure (e.g., building or ship structure such as a floor, wall, or ceiling) having an opening (such as a hole for passage or access to cables, wires, pipes, ducts, electrical panels, etc.), or providing first and second structures which define therebetween a gap (such as the joint gap between a wall and a ceiling or floor); introducing into the opening or gap at least one (empty) thermal barrier molding bag that is operative to receive and substantially to contain a flowable firestop material, one that is preferably operative to harden within the bag; and introducing into the thermal barrier molding bag a flowable firestop material to expand the bag within the hold or joint gap, thereby creating a thermal barrier within the hole or gap.
Exemplary thermal barrier molding bags of the invention are preferably made of thermoplastic film material (although other suitable materials are hereinafter described) and preferably have at least two or more openings, preferably of the type that can be opened and closed more than once, that permit introduction into the bag of a flowable firestop material, e.g., such as hydratable cementitious slurry, an intumescent material, a superabsorbent polymer; polyurethane (foam); hydrated silica gel; inorganic dessicants (e.g., molecular sieves such as zeolites; silica gel; calcium oxide; calcium sulfate; calcium chloride; barium oxide; phosphorous pentoxide); fibers; mineral wool; fiber glass; or mixture thereof. The molding bag material should be sufficiently sized and shaped, and flexible enough to permit expansion of the molding bag, upon introduction of the flowable firestop material, and to permit molding of a thermal barrier within at least a portion of the opening or joint gap. Preferably, the bags are flexible enough to permit them to be transported in a compact rolled form (when empty) and unrolled into place in the opening or gap space (wherein they are expanded and filled with the flowable firestop material).
Firestop barriers made in accordance with the above-described in-situ methods of the present invention provide excellent fire resistance and sealing ability as well as smoke and acoustic barrier properties. They are also sufficiently strong to resist dislodgement from the gap or opening due to pressure (e.g., force from a water hose) and are highly amenable to visual inspection.
Further features and advantages of the invention are described in detail hereinafter.